Wish I had time to build one of these myself! A few other things in the queue....
Wayne N6KR > On Jan 23, 2019, at 6:32 AM, 'Dale Parfitt' pari...@frontier.com [KX3] > <kx3-nore...@yahoogroups.com> wrote: > > > HI Wolf, > > VK3YE could have done so much better from an efficiency standpoint without > making the loop any larger. > > 1. Flat metal stock is not as efficient as round stock (of the same > circumference) because current crowding at the edges of the rectangular stock > makes it appear smaller in surface area. > > 2. A much lower D capacitor such as a dual gang air variable with the gangs > in series (to avoid resistive losses in the bearings) or a butterfly would > also have aided in higher efficiency. > > 3. Copper would have helped efficiency somewhat with its lower RF resistance > and ability to be soldered versus mechanical connections, but that is > partially offset by aluminum’s larger skin depth. Of course copper is heavier > and more expensive, but in tube form the weight issue could be minimized.. > > > > Just some thoughts. Again, the VK1OD calculator allows one to make precise > efficiency measurements so even small improvements can be measured. As an > example, the difference in efficiency between using braided coax as the loop > radiator versus hardline or copper tubing is readily apparent. For the same > diameter loop and same conductor diameter, a narrower bandwidth means higher > efficiency. > > > > Dale W4OP > > > > From: k...@yahoogroups.com [mailto:k...@yahoogroups.com] On Behalf Of 'Wolf > Hoeller, OE7FTJ' wolf.oe7...@gmail..com [KX3] > Sent: Wednesday, January 23, 2019 4:57 AM > To: k...@yahoogroups.com > Subject: Fwd: [KX3] Urban stealth HF: Inside-the-backpack loop antenna? > > > > > > Wayne, > > > > a really good idea. > > Have a look at VK3YE's youtube channel for his experiment to put a loop > antenna in (frame of) a notebook bag. > https://www.youtube.com/watch?v=BC5lFbLqaeg > > > > Another good idea for a stealth antenna has the spain company Inac. Here is > the suitcase with a loop inside the frame: > https://www.inac-radio.com/MAK721PRO > > > > I would like the idea, to sit in an urban park with my backpack or similar on > my knees and make some contacts. > > > > > Wolf, OE7FTJ > > Emergency Communications via Winlink Global Radio Email ®️ > > > > > > > > Am Di., 22. Jan. 2019 um 21:57 Uhr schrieb Wayne Burdick n...@elecraft.com > [KX3] <kx3-nore...@yahoogroups.com>: > >> >> >> I’ve engaged in plenty of ultralight HF pack operation, with a KX2, AX1 >> antenna and a dragged counterpoise. In wide open spaces it’s a blast. But >> urban settings with dogs, wire-eating cacti and overzealous Neighborhood >> Watchers can distract from one’s radio experience. >> >> >> >> So, just for grins, I’d like to try something completely incognerdo: no >> visible antenna. A small remotely tuned loop (say 12” diameter) would seem >> to be the best choice, as it would fit entirely inside a small backpack. It >> could have modest efficiency while not requiring a counterpoise wire. Rigid >> 1” copper pipe formed in a square would be convenient to deploy. >> >> >> >> The loop would be only 6 to 8” from soft tissue, so you’d want to run QRP, >> of course. OTOH, we’re talking about HF. A cellphone by your ear is >> probably worse. >> >> >> >> Any other antenna suggestions? >> >> >> >> Wayne >> >> N6KR >> >> >> >> >> > > > __._,_.___ > Posted by: "Dale Parfitt" <pari...@frontier.com> > Reply via web post • Reply to sender • Reply to group > • Start a New Topic • Messages in this topic (2) > > Have you tried the highest rated email app? > With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app > on the market. What are you waiting for? Now you can access all your inboxes > (Gmail, Outlook, AOL and more) in one place. Never delete an email again with > 1000GB of free cloud storage. > VISIT YOUR GROUP > • Privacy • Unsubscribe • Terms of Use > > SPONSORED LINKS > > > > . > > > __,_._,___ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
